Method of varying the effective force on a driven fastener by a powder charge of constant magnitude



J y 1955 v. R. ERICKSON ETAL 2,713,166

METHOD OF VARYING THE EFFECTIVE FORCE ON A DRIVEN FASTENER BY A POWDER CHARGE OF CONSTANT MAGNITUDE Original Filed Dec. 29, 1949 9 INVENTORS V/26/N/U5 A ii/a sa/v BY @I/VJAM/N a. az/uw/Ami imam [r METHOD OF VARYING THE EFFECTIVE FORCE ON A DRIVEN FASTENER BY A POWDER (JEARGE OF CONSTANT MAGNITUDE Virghiius R. Erickson and Benjamin B. Bullwinkle, Portland, Greg, assignors to Powder-Power Tool Corp'., Portland, Greg, a corporation of Oregon Original application December 29, 1949, Serial No. 135,744. Divided and this application April 30, 1954, Serial No. 426,788

2 Claims. (Cl. 1-60) This application is a division of our copending application Serial No. 135,744, filed December 29, 1949, for Stud Driving Tool and Method of Power Control.

The present invention relates to stud driving tools of the type employed for the explosive installation of studs in various types of concrete and steel structures, and is concerned particularly with methods and apparatus for employing standard explosive charges all of the same magnitude by varying the effective force of such charges as applied to the studs to obtain a desired selected force for successful installation of a particular stud in a particular wall surface.

The present invention provides for varying of the combustion space or chamber in which the explosive charge is exploded and for also varying the spacing of the stud from the muzzle end of the barrel to influence further the energy imparted to the stud by controlling the time during which the stud is subjected to the driving force before emerging from the muzzle end of the barrel. This varying of the efifective force is carried out by providing a stud positioning rod which can be inserted through the breech end of the barrel and which carries graduations so that the stud can be pushed along the barrel to a desired selected location.

The above and other objects of the invention are attained in connection with certain preferred embodiments of the invention as disclosed and described in connection with the accompanying drawings, in which:

Figure 1 is an elevational view of a stud driving tool with certain parts broken away and shown in section to illustrate the combustion chamber of the tool.

Figure 2 is a view of a stud setting rod to position the stud along the barrel as desired by the operator.

Referring to Figure 1, there is shown a stud driving tool of the character described and claimed in the copending applications of Smith and Daugherty, Serial No. 124,078, filed October 28, 1949, for Stud Driving Tool, and Erickson and Bullwinkle, Serial No. 130,818, filed December 2, 1949, and issued as U. S. Letters Patent No. 2,679,645, on June 1, 1954, for a Safety Pad for Stud Driving Tools. In general, stud driving tools of this character are adapted to be separated or broken into two halves including a rear part 10 which contains the various firing control parts including, for example, a firing pin carrier 11, and a front or barrel part 12 of the tool in which the barrel 13 is included. The barrel 13 is provided with an enlarged rear end 13:: which has a threaded connection within the end of the firing pin carrier 11 to connect the two halves of the tool. The barrel 13 is also provided with an enlarged bore in which a breech plug insert 14 is provided in which the explosive cartridge 18 is mounted Patented July 19, 1955 extent of positioning of the stud within the barrel. The grooved graduations 22b correspond to certain commonly used stud positions. The rod 22 carries a stop or limit collar 23 for cooperation with the graduations, the collar 23 being held in place on the rod by a set screw 24.

The reduced end 220 of the stud positioning rod 22 may be employed for removing a cartridge 18 from the breech plug when it becomes stuck because of expansion during the explosion process.

With the parts disassembled, the breech plug or insert 14 is removed and the selected stud 16 is installed in the barrel by being pushed along the bore of the barrel by the rod 22, the collar 23 having been adjusted to one of the graduations 2241 or 22b to control the position of the stud and its distance from the cartridge. The cartridge 18 is then placed in the breech plug 14, and the parts are reassembled as shown in Figure 1 for a firing operation. Firing is accomplished by placing the end of the barrel 13 against the surface into which the stud is to be driven and pressing or telescoping the barrel assembly 12 and the firing pin carrier 11 back into the other part of the tool until a firing position is reached, as disclosed in said applications, and then effecting relative turning movement of the central housing and the end grip to fire the tool. At this time the deflector pad structure 19, yieldably mounted about the barrel 13, is engaged with the surface about the area of engagement of the end of the barrel so as to provide protection from flying particles of the wall surface upon explosive installation of the stud.

From the foregoing description, it will be appreciated that the invention employs a stud positioning insert or member having portions of varying width, including a portion extending from one end of the insert of less width than the width of the stud receiving and guiding bore,

= and a portion of greater width than the width of the bore which engages a portion of the barrel to form a limit stop. It will also be appreciated that the method in which this insert is used contemplates the control of the eflective force of explosive charges all of the same magnitude by variably utilizing the placing of the stud at any one of a plurality of locations between the ends of the bore to control the length of the bore forming a part of the combustion chamber and to control the length of the bore utilized to guide the stud when it is being expelled from the tool. Hence, the degree of penetration of the stud through the surfaces of various types of material can be readily controlled in accordance with the characteristics and type of material which the stud is adapted to penetrate.

While we have shown and described certain preferred methods and apparatus for carrying out the invention it will be understood that the invention is capable of variation and modification from the form shown so that its scope should be limited only by the scope of the claims appended hereto.

We claim:

1. The method of installing successive studs in surfaces by subjecting each stud to an explosive driving force in a stud driving tool having a barrel provided with a breech end and a muzzle end, which comprises providing a member adapted to be inserted in said barrel and having a plurality of means to enable location of a stud in said barrel at any one of a. plurality of distances from the breech end of the barrel, inserting each stud through the breech end of the barrel to be wholly enclosed within the bore of the barrel and fixing the distance at which the inserted stud is to be positioned from said breech end by insertion of said member in said barrel and pushing the stud to a selected position in said barrel as determined by selecting one of said means, and installing for each stud a cartridge containing an explosive charge of constant magnitude at said breech end, the selected location of the inserted stud in said barrel with respect to said cartridge fixing the size of the combustion chamber for the firing of each stud and the amount of travel of each stud along the barrel to be expelled therefrom and thereby controlling the effective force imparted to each stud upon exploding a charge.

2. The method of controlling the effective force of different explosive cartridges, all of the same magnitude, against studs in a stud-driving tool to control the extend of penetration of each stud, respectively, in material in accordance With the type of material into which each stud is to be driven, said tool having a bore provided with a breech end and a muzzle end and along which each stud can be positioned at varying distances from the breech end, the breech end of said bore constituting a chamber to receive means carrying an explosive charge, said method comprising providing a member adapted to be inserted into an end of said bore and having a plurality of means to enable location of each stud in said bore at any one of a plurality of positions of predetermined distances from the breech end of said bore When the studs, respectively, are in abutment With an end thereof, inserting a stud in said bore through one end thereof, then positioning said stud at a predetermined distance from the breech end of said bore by inserting said member in through the same end of said bore and by engaging and pushing the inserted stud with said member, and finally terminating said pushing action at the selected predeterminedposition in said bore as enabled by said means, and thereafter removing said member from said one end of said bore.

References Cited in the file of this patent UNITED STATES PATENTS l,445.l26 Bergman Feb. 13, 1923 FOREIGN PATENTS 308,476 Germany Oct. 29, 1920 

